Astron. Astrophys. 324, L29-L32 (1997)

1. Introduction

The origin of type II supernovae (SNe) seems to be mainly well understood. The final collapse of the core of a massive star is followed by an SN explosion leaving behind a neutron star or a black hole. However, because of extensive mass-loss in the preceding stages it is not yet possible to predict which main sequence mass produce particular SNII subtypes, and whether the core collapse takes place in a red or blue supergiant. The light curves and spectra of SNe are also strongly influenced by the surrounding circumstellar medium. Clearly, systematic investigations and physical modelling of the spectral characteristics and time behaviour of the various SNII subtypes are required before the above mentioned questions can be answered.

In recent years, besides the classical type II SNe, hydrogen rich subtypes have been discovered and studied, e.g. SN 1987F with a pure emission line spectrum which at certain phases was similar to Seyfert 1 spectra (Filippenko 1989), or SN 1988Z with pure broad and narrow emission features (Stathakis & Sadler 1991, Turatto et al. 1993). Both supernovae faded unusually slowly. Terlevich et al. (1992) have suggested that these characteristics originate from the interaction of SN explosions with dense circumstellar gas and have called these objects compact supernova remnants. In this letter we report on the serendipitous discovery (Hagen & Reimers 1997) of a further 'Seyfert 1' type II supernova which due to its brightness and apparently slow fading is a promising target for a study of the longterm behaviour of compact SN remnants.

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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